Pin-efficient reader bias enable control

ABSTRACT

Systems and methods are included for determining a presence of an upcoming reading field during a write mode of a storage device, and initiating a read-while write (RWW) mode of the storage device in response to the sensed reading field. Initiating the RWW mode comprises warming up the reader circuitry, generating a signal in response to an end to the write operation, and activating reader bias current in response to the generated signal.

SUMMARY

Some embodiments described herein involve systems and methods fordetermining a presence of an upcoming reading field during a write modeof a storage device; and initiating a read-while write (RWW) mode of thememory device in response to the sensed reading field. In some cases,initiating the RWW mode comprises warming up the reader circuitry,generating a signal in response to an end to the write operation, andactivating reader bias current in response to the generating signal.

In some cases, sensing the reading field comprises sensing at least oneof a timing field or a servo field. According to variousimplementations, activating the reader bias current occurs after warmingup the reader circuitry. According to various aspects, the writeoperation is an alternating signal. In some cases, the end to the writeoperation is an end to an alternating signal. In some cases, warming upthe reader circuitry occurs during an alternating write signal.

According to various embodiments, generating the signal comprisesgenerating the signal using a serial interface of a preamplifier of thememory device. In some cases, the RWW mode lasts until a majority of thereading field is read. In some implementations described herein, the RWWmode ends before a majority of the reading field is read. For thepurposes of this section, majority means more than 50% of the field isread.

Some embodiments described herein may include systems and methods fortransferring configuration data packets to a preamplifier using a serialdata port during a first time period and using one or more output pinsof the serial data port to enable a function during a second timeperiod. According to various implementations, the first time period isduring a time in which no reads or writes are occurring. In some cases,transferring data packets to a preamplifier further comprisestransferring data packets used to configure reading and writingpreamplifier registers. According to various implementations, one ormore pins using of the serial data port are used to transmit signals toenable a reader bias current during the second time period.

In some cases, the function is an RWW function. According to variousembodiments described herein, enabling a RWW comprises initiating awarm-up of read circuitry during a write mode of the memory device,ending an alternating write signal at a predetermined amount of timeafter the initiation of the warm-up of the read circuitry, and using theserial data port to transmit a reader bias current enable signal afterthe ending of the alternating write signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a process of switching from a write mode to an RWWmode according to various implementations;

FIGS. 2A-2C are timing diagrams that illustrate a transition from awrite mode to a RWW mode in response to a determination of an upcomingreading field in accordance with embodiments described herein;

FIG. 3 is a block diagram of a computing system capable of performing areader bias current enable at a different time than the reader circuitryaccording to various embodiments;

FIG. 4 illustrates a block diagram of a hard drive apparatus capable ofperforming a reader bias current enable at a different time than thereader circuitry in accordance with various implementations;

FIG. 5A is a flow diagram that describes a process that uses the serialinterface to enable the reader bias current according to variousembodiments;

FIG. 5B is a schematic diagram illustrating the use of a serialinterface output to develop an enable signal for gain control;

FIG. 5C is a more detailed flow diagram illustrating a process forswitching from a write mode to an RWW mode using a serial interface toenable the reader bias current in accordance with embodiments describedherein;

FIGS. 6A and 6B illustrate the signals that are used by the SIF inaccordance with various implementations;

FIG. 7 is a diagram of a circuit that is capable of using the serialinterface signals to enable a reader bias current of a memory device inaccordance with various implementations; and

FIGS. 8A-8B are timing diagrams that use a pulse on the serial Clock pinto enable the reader bias current in accordance with embodimentsdescribed herein.

DETAILED DESCRIPTION

In memory storage devices, it can be useful to have read and writefunctionality enabled simultaneously. Switching to read mode afterending write mode may cause efficiency loss because read circuitry takestime to warm up. Enabling a read operation while a write operation istaking place allows the read circuitry to warm up during a writeoperation. Once the write is finished and a reading field is ready to beread, the read circuitry is already warmed up. Reader bias current canalso be enabled in addition to the reader circuitry in order to readfrom the memory storage device. The reader bias current circuitry takesa shorter time to warm up than the reader circuitry. Reader bias currentis often enabled in response to enabling as the reader as the readercircuitry. Enabling the reader bias current at the same time as thereader circuitry may be problematic, however, in a read-while-write(RWW) mode because having the reader bias current enabled at the sametime that a write signal is alternating may shorten the lifespan of theread/write transducer heads of the memory device. According to variousaspects, the reader circuitry is circuitry that amplifies a read signaland the reader bias circuitry allows a predetermined direct current intoa read transducer of the memory device when enabled.

It may be beneficial to enable the reader bias current at a differenttime than the reader circuitry to account for the time difference of thewarm up times of the read circuitry and the reader bias circuitry. Insome cases, the reader bias current is enabled at a later time than thereader circuitry, allowing a write operation to continue while thereader circuitry is warming up. The reader bias current may be enabledafter the write signal stops alternating. According to variousembodiments described herein, the reader bias current is enabled by apulse on a serial interface pin of the preamplifier.

FIG. 1 illustrates a process of switching from a write mode to an RWWmode. The presence of an upcoming reading field is determined 110 duringa write mode of a memory device. The write mode may involve analternating write signal and/or current. The reading field may be atiming field and/or a servo field, for example. In response to thesensed reading field, a RWW mode of the memory device is initiated 120.The reader circuitry is warmed up 130 during the write operation. Asignal is generated 140 in response to an end to a write operation. Insome cases, the write operation comprises an alternating write signalThe alternating write signal may ended at a time after the readercircuitry has started to warm up. In some cases, the alternating writesignal stops a predetermined period of time after the RWW mode isinitiated. In some implementations, the alternating write signal stopson completion of the warm up of the reader circuitry. According tovarious embodiments, the alternating write signal stops a predeterminedperiod of time before the reading field. A reader bias current isactivated 150 at substantially same time as or after the alternatingwrite signal is stopped. Once the reader circuitry and the reader biascurrent are warmed-up, the reading field may be read and/or demodulated.After the reading field is read and/or demodulated, the RWW mode may endcausing the reader circuitry and the reader bias current to power downand the write signal to begin alternating again to continue with a writeoperation. In some cases, the write circuitry is powered down during thereading of the reading field and the reading field is read during a readmode. According to various embodiments, after the reading field is read,the device enters an idle mode in which no reads and/or writes areoccurring.

FIGS. 2A-2C are timing diagrams that illustrate a transition from awrite mode to a RWW mode. FIG. 2A shows an example in which a write modeis initiated at time 205 from an idle mode. The device starts to switchto an RWW mode in response to a determination of an upcoming readingfield that starts at time 230. The device may initiate a switch from awrite mode to a RWW mode at a predetermined time period before thebeginning of the reading field, for example. The switch from the writemode to the RWW mode begins at time 210 at which time the readercircuitry starts to warm up. The reader circuitry is warmed up startingat time 210 and ending at time 225, before the start of the readingfield. The write signal continues to alternate until the readercircuitry is warmed-up, at time 225. The reader bias current circuitryis enabled at substantially the same time as the reader circuitry, attime 210, and takes from time 210 to time 215 to activate. As is shownin the figure, the reader circuitry takes more time to warm up than thereader bias current circuitry.

According to FIG. 2A, the write signal is alternating at the time thatthe reader bias current circuitry is activated. As can be observed, thereader bias current and the alternating write signal overlap from time215, until time 225. Having the reader bias current activatedconcurrently with an alternating write signal may cause electrical overstress, which may compromise the head life and thus may result in ashorter lifespan for the device. After the reading field, the RWW modeends and a write mode begins, at time 235. Ending the RWW mode includesdisabling the reader circuitry and the reader bias current. The writesignal begins to alternate again in response to the switch from a RWWmode to a write mode.

One way that may be used to decrease the probability of experiencingelectrical overstress is by ending the alternating of the write signalat an earlier time. FIG. 2B shows an example in which the alternatingwrite signal is stopped a period of time before the reader bias currentis initiated. Ending the alternating write signal before or atsubstantially the same time as the reader bias current is enabled mayreduce the probability of electrical overstress. As can be observed fromFIG. 2B, the alternating write signal is initiated at the same time asin FIG. 2A, at time 205. A determination is made that there is anupcoming reading field. In preparation for the upcoming reading field,the device prepares to transition from a write mode to a RWW mode. Thealternating write signal is stopped at an earlier time, at time 207,than in FIG. 2A, to minimize the chance of an overlap of the alternatingwrite signal and the reader bias current. In the example of FIG. 2B, thealternating write signal stops at a time before the initiation of theRWW mode, at time 210. In some implementations, the alternating writesignal stops a predetermined period of time before the initiation of theRWW mode. In some cases, the alternating write signal stops atsubstantially the same time as the initiation of the RWW mode. Thereader circuitry and the reader bias current start warming up at time210. The reader circuitry takes from time 210 until time 225 to warm upin preparation for the upcoming reading field. Again, as in FIG. 2A, thereading field lasts from time 230 until time 235. At time 235 the devicetransitions back to a write mode by disabling the reader circuitry andthe reader bias current and by starting the alternating write signal.

According to FIG. 2B, the write operation is suspended during the timethat the read circuitry is warming up. Format loss occurs as a result ofthe lack of writing that is occurring during the warm up of the readercircuits, from time 210 to time 225. It may be beneficial to allow thewrite signal to continue to alternate during a warm-up of the readercircuitry and before enabling the reader bias current.

FIG. 2C illustrates an example in which the reader circuitry is warmedup at an earlier time than the reader bias current circuitry isactivated. According to FIG. 2C, the reader bias current is enabled at alater time than the reader circuitry allowing the reader circuitry towarm-up at the same time that a write is taking place withoutpotentially causing electrical overstress. As in previous examples, awrite mode begins at time 205. At time 210 a switch from write mode toRWW mode is initiated and the reader circuitry begins to warm up. Thereader circuitry finishes warming up at time 225. The write signalcontinues to alternate until time 227, at which time the reader biascurrent is activated. In some cases, the reader bias current isactivated after a predetermined amount of time after a determination ismade that the write signal has stopped alternating. In someimplementations, the reader bias current is activated at substantiallythe same time that the alternating write signal stops. The readercircuitry and the reader bias current circuitry are substantiallyoperational before or at substantially the same time as the start of thereading field, at time 230. The reading field lasts from 230 to 235 atwhich time the reader circuitry and the reader bias current aredisabled. Once the reader bias current is disabled, the alternatingwrite signal starts back up to continue the write operation. Thealternating write signal may not start back up until a determination ismade that the reader bias current is completely disabled.

FIG. 3 is a block diagram of a computing system capable of performing areader bias enable at a different time than the reader circuitry. FIG. 3includes a host 310 and a memory device 320. The memory device 320includes a controller 330 and memory 340. The host 310 may be any typeof computing system. The controller 330 facilitates communicationbetween the host 310 and the memory 340. The memory may be of varioustypes comprising, magnetic data storage drives and/or hybrid drives thatincorporate both magnetic drives and solid state media.

The techniques and structures described herein may be used, for examplein a magnetic data storage device such as a hard drive. A hard drivegenerally includes at least one magnetic disk that rotates around aspindle axis. The drive further includes one or more transducer headspositioned over a surface of the disk while reading from or writing tothe disk.

The one or more transducer heads may include both magnetic read andwrite heads. A reader generally operates by detecting a changingmagnetic field, e.g., changes in direction of magnetic flux caused byrelative motion between an encoded magnetic media and the read head. Thewriter operates in response to a write current which generates amagnetic field at a tip of a write pole. This magnetic field in turnschanges the orientation of a local magnetic field local at the surfaceof the disk, causing data to be persistently stored on the disk. Apreamplifier circuit can be used to apply current to the heads. Thepreamplifier may include a serial interface that can be used to enablethe reader bias current at a different time than the reader circuitry.

The reader bias current may be enabled at a different time than thereader circuitry in a variety of ways. In some cases, the reader biascurrent is initiated at a different time than the read circuitry byusing an existing serial interface (SIF) for the preamplifier. The SIFis conventionally used for serial transfer of packets used to read andwrite preamplifier registers, but may, according to various embodimentsdescribed herein, be used to issue a signal to enable a reader biascurrent at times in which the transfer of packets is not occurring.

FIG. 4 illustrates a block diagram of a hard drive apparatus inaccordance with embodiments described herein. The apparatus may becoupled to a host device via a host interface 405. The host device mayinclude any electronic device that can be communicatively coupled tostore and retrieve data from an HDD, e.g., a computer or a server.According to various embodiments, during a write operation, thecontroller 415 may determine that there is an upcoming reading field. Inresponse to the determination, the controller 415 sends a signal to thepreamplifier to initiate a switch from a write mode to an RWW mode. Thesignal to start RWW mode 425 causes the read circuitry to start warmingup. At a predetermined time before the reading field, the controller 415stops the write signal from alternating. After or at the same time thatthe write signal stops alternating, the controller and/or read channelsends a reader bias enable signal 435 to the serial interface masternode 447. The reader bias enable signal 435 tells the serial interfaceto issue a pulse that causes the reader bias current circuitry to turnon. A serial interface signal is sent to the serial interface slave node449 to send a signal to enable the reader bias current. The bias currentsource switch is closed allowing the reader bias current to be enabledin response to the pulse. Once the read circuitry is warmed up and thereader bias current circuitry is turned on, the reading field may beread by the device. During the reading field, the head assembly 455allows data to be read from the storage media 465.

FIG. 5A is a flow diagram that describes a process that uses the serialinterface to enable the reader bias current. According to FIG. 5A,configuration data packets are transferred 510 to a preamplifier using aserial data port during a first time interval. In some cases, the firsttime period occurs when no media read or write activity is occurring. Inother cases, the first time period may occur during a read and/or writeoperation. During a second time period at least one pin of the serialdata port is used 520 to transmit a signal that enables a function ofthe preamplifier, such as an RWW function, for example. The second timeperiod may occur while any read and/or write operation is occurring orin preparation for an RWW mode, for example. In some cases, the secondtime period takes place during an RWW mode of the memory device.

In some cases the serial interface is used to issue a pulse to enableother functionality of the device. For example, the serial interface maybe used to issue a signal that enables a transistor that may be used toreduce a gain in a read data path during a timing latency testing suchas an existing depletion field effect transistor (DFET) within thepreamplifier, for example. This may be used, for example, in a hard diskdrive that manages a large capacity of information being written to andretrieved from the media controlled by the drive. Such systems usepositioning by reference to the read location in order to determine thecorrect write location. To do so requires an adjustment between the readlocation to account for the small distance between the read head and thewrite head for the write operation. In addition to the actual distance,the latency due to the electronics may also be taken into account. Insome cases, measuring the round-trip latency for the read and writepaths causes the read/write paths to become saturated making latencymeasurement difficult. Enabling the existing DFET using the serialinterface allows for the gain of the read data path to be reduced sothat an accurate latency measurement can be made. FIG. 5B illustratesone example technique for developing the enable signal (DFET_EN) for theMOSFET to provide gain control. This example includes using a output ofa serial interface (SIF) of the read preamplifier to provide the DFET_ENsignal during latency testing. As previously discussed, the SIF may beused to transfer serial configuration data from the controller to thepreamplifier. Any output of the SIF may be used for DFET_EN so long asthe timing of the use of the SIF output for DFET_EN does not conflictwith the other uses for the output. For example, if SCLK is used todevelop the DFET_EN signal, the SCLK signal would be used for DFET_ENduring periods that it was not otherwise being used, e.g., to clock inconfiguration data from the controller.

The reader bias current is generally substantially zero during thetiming latency testing to prevent potential damage to the readtransducer. The bias current enable signal (IMR_EN) enables the readerbias current. The gain control element (the DFET) is enabled only whenthe IMR_EN is low. In the example shown in FIG. 5B, the SCLK output ofthe SIF provides the reader bias current enable IMR_EN. The inverse ofthe IMR_EN signal is ANDed with the Write/Read Mode signal (WRn) toproduce DFET_EN. It will be appreciated that there are many other waysto derive the DFET_EN that involve dual purpose use of a signal that isused during other times for a function other than DFET_EN. The dualpurpose SIF implementations discussed above may allow for the use ofexisting components in the read path to derive various other controlsignals.

FIG. 5C is a more detailed flow diagram illustrating a process forswitching from a write mode to an RWW mode using a serial interface toenable the reader bias current. A presence of an upcoming reading fieldis determined 530 during a write mode of a storage device. A RWW mode isinitiated 540 in response to the upcoming reading field. The readercircuitry is warmed up 550. The alternating of the write signal is ended560. In some cases, ending the write signal means switching from analternating write signal to a DC write signal. Using an RWW mode duringthe reading of the timing field allows the write circuits to remainactive during the reading of the reading field facilitating a fastswitch from the RWW mode back to a write mode. According to variousimplementations, ending the alternating write signal means switchingfrom an RWW mode to a read mode so that the write circuits are powereddown during the reading of the reading field. After the alternatingwrite signal has ended, the reader bias current is enabled 570 byissuing a pulse on the serial interface. The reading field is read 580once the reader circuitry and the reader bias current circuitry havewarmed up. After the reading field is read, the reader circuitry and thereader bias current circuitry are disabled and powered down 590. In somecases, after the reading field is read, the RWW mode ends and a writeoperation continues by powering down the read circuitry and the readerbias current circuitry. In some cases after the read circuitry and thereader bias current circuitry are powered down, the device switches toan idle mode.

FIGS. 6A and 6B illustrate the signals that are used by the SIF. Threesignals are used, a Data signal 610, an Enable signal 620, and a Clocksignal 630. The Enable signal 620 is asserted to instruct thepreamplifier that a transfer of serial data is starting. Bits are sentout on the data signal and the Clock signal 630 is used to clock theaddress bits to the preamplifier serial interface logic and data bits toor from the addressed preamplifier register. Once the bits have beentransferred to and/or the preamplifier's register, the Enable signal 620de-asserts. In some cases, the Clock signal 630 is ignored when theEnable signal is de-asserted. According to various embodiments, when theEnable signal 620 is de-asserted, the Clock 630 signal can be used forother purposes, such as for a signal to enable the reader bias current.

FIG. 7 is a diagram of a circuit that is capable of using the serialinterface signals to enable a reader bias current of a memory device.Using the circuit of FIG. 7, the SIF can be used to control the readerbias current enable 700 in conjunction with a transition from write modeto RWW mode. In some implementations, the functionality of enablingreader bias current upon entering read mode may also be retained. Insome cases, control of reader bias current enable can be used any timeread functionality is enabled, either by entering read mode from idle orentering RWW mode from write mode. In some cases, the SIF Enable signalis used to discriminate between the use of the Clock signal as a SIFclock and as a reader bias current enable signal.

According to the diagram of FIG. 7, when Rd_Enable is de-asserted, theflip flop 705 is unconditionally held reset, disabling reader biascurrent, and the SIFsignals can be used for serial interface transfers,having no effect on reader bias current control. The flip-flop 705 ofFIG. 7 is a Reset-Overrides-Set type so the Set input has no effect whenRd_Enable is de-asserted. When Rd_Enable is asserted, the flip flop maybe set by a pulse on its S input allowing the reader bias current enable700 to be asserted.

A configuration bit may be used to determine whether the SIF control ofthe reader bias current is in effect for RWW mode or for both RWW andread modes. If the configuration bit is asserted, the Wr_Enable signalhas no effect, so the flip flop 705 is enabled to be set either in readmode or RWW mode. In some cases, the flip flop 705 is set by a low-goingpulse on Clock while the SIF Enable is held de-asserted. When a SIFtransfer is not active, Enable is low and Clock is held high. Accordingto the diagram of FIG. 7, if the configuration bit is de-asserted, thenthe flip flop's Set input is asserted whenever Wr_Enable is low. Thus inthe configuration of FIG. 7, bias current is enabled upon entry intoread mode (Rd_Enable asserted, Wr_Enable de-asserted), but stillcontrolled by Clock when entering RWW mode. In some cases, SIF transfersmay continue after a RWW mode is enabled up until substantially the timethat the reader bias current is enabled. In some cases, the Enable isheld high when a low going pulse is issued on the Clock allowingon-going SIF transfers to overlap the interval between the time RWW modeis first enabled and when the Clock pulse is issued to enable biascurrent.

The circuit of FIG. 7 allows read functionality to be enabled withoutautomatically enabling bias current. The bias current may be enabled bya subsequent pulse on the Clock pin allowing RWW mode to be enabledarbitrarily early when writing without risk of electrical overstress. Toprevent electrical overstress, the controller, having the ability tocontrol the timing of events relative to the media format, generates apulse on Clock when the alternating write signal has ceased.Additionally or alternatively, the controller may determine that no SIFtransfers are in progress between the time RWW is enabled and when thepulse on the Clock line is issued to enable bias current. In some cases,the controller can buffer serial interface packets issued by firmwareduring a “blackout window” prior to entering RWW, and can issue thebuffered SIF packets after the RWW mode ends. In some cases, SIF packetsare not issued during time periods in which the device is in a writeand/or read mode. According to various implementations, reader biascurrent is disabled at substantially the same time as the readfunctionality is disabled. In some cases, the reader bias current isenabled at a different time than the read circuitry by using a faultsignal output by the preamplifier to the controller.

FIGS. 8A-8B are timing diagrams that use a pulse on the serial Clock pinto enable the reader bias current. FIG. 8A illustrates a diagram inwhich a switch from a write mode to an RWW mode is initiated by adetermination of an upcoming timing field. Timing fields can be used indevices utilizing bit patterned media to read and/or demodulate timingfields interspersed in the data fields, for example. In some cases,enabling an RWW mode allows the device to avoid the overhead ofdisabling and re-enabling write functionality before and after thetiming fields. According to various implementations, the preamplifiercontinues writing while the timing field is read and/or demodulated.During the reading and/or demodulating of the timing field, the flow ofwrite data to the preamplifier may be suspended and DC writing is doneduring this time.

In some cases, the read circuitry is warmed up in response to adetermination of an upcoming timing field at time 810. While the readcircuitry is warming up, from time 810 to time 815, the write signalcontinues to alternate as is shown in FIG. 8A. At a predetermined periodof time before the timing field, the alternating write signal is stoppedand switches to a DC write signal at time 817 and a pulse on the serialclock is issued that allows the reader bias current to be enabled. Thereader bias current is activated from about time 817 to time 820, andthe timing field is read and/or demodulated from about time 820 andending about at time 830. Once the timing field is read, the deviceswitches back to a write mode by disabling and powering down the readcircuitry and the reader bias current circuitry and the write signalbegins to alternate again without having to warm up the write circuitry.

FIG. 8B illustrates another example in accordance with embodimentsdisclosed herein. According to FIG. 8B, a determination that a servofield is coming up prompts the switch from a write mode to an RWW modeat time 812. FIG. 8B illustrates a diagram in which a switch from awrite mode to an RWW mode is initiated by a determination of an upcomingservo field. Servo fields can be used in devices utilizing continuousmedia to read and/or demodulate servo fields interspersed in the datafields, for example. The determination of an upcoming servo fieldenables the read circuitry allowing it to warm up, from time 812 to time816, while the write signal continues to alternate. A predeterminedperiod of time before the servo field, the write signal stopsalternating at time 818, allowing the reader bias current circuitry tobe activated from about time 818 to about time 822. Before or atsubstantially the same time as the servo field begins the RWW mode endsand read mode begins. The reader bias current circuitry is enabled by asignal issued by the serial Clock. At the time that the servo fieldstarts, the reader circuitry and the reader bias circuitry aresubstantially operational. The servo field is then read from time 822 totime 832, while in read mode. At the end of the servo field, at abouttime 832, the read mode ends, disabling the reader circuitry and thereader bias current. In some cases, the reader circuitry and the readerbias current are not disabled at the end of the servo field.

It is to be understood that this detailed description is illustrativeonly, and various additions and/or modifications may be made to theseembodiments, especially in matters of structure and arrangements ofparts. Accordingly, the scope of the present disclosure should not belimited by the particular embodiments described above, but should bedefined by the claims set forth below and equivalents thereof.

What is claimed is:
 1. A method, comprising: determining a presence ofan upcoming reading field during a write mode of a storage device; andin response to the determining step, initiating a read-while write (RWW)mode of the storage device comprising: warming up reader circuitry;generating a signal in response to an end to a write operation; andactivating a reader bias current in response to the generating step. 2.The method of claim 1, wherein determining the presence of the upcomingreading field further comprises, sensing at least one of a timing fieldor a servo field.
 3. The method of claim 1, wherein activating thereader bias current further comprises activating the reader bias currentafter warming up the reader circuitry.
 4. The method of claim 1, whereinthe write operation is an alternating write signal.
 5. The method ofclaim 4, wherein warming up the reader circuitry occurs during thealternating write signal.
 6. The method of claim 1, wherein generatingthe signal comprises using a serial interface of a preamplifier.
 7. Themethod of claim 1, wherein the RWW mode lasts until a majority of thereading field is read.
 8. The method of claim 1, wherein the RWW modeends before a majority of the reading field is read.
 9. A deviceconfigured to enable a read-while write (RWW) mode in a non-volatilestorage device comprising: a controller configured to determine apresence of an upcoming reading field during a write mode of thenon-volatile storage device; preamplifier circuitry configured to switchfrom the write mode to the RWW mode and warm up reader circuitry inresponse to the upcoming reading field; and serial interface circuitryconfigured to generate a first signal in response to an end to a writeoperation, the preamplifier circuitry configured to activate a readerbias current in response to the first signal.
 10. The device of claim 9,wherein the controller is further configured to sense at least one of atiming field or a servo field.
 11. The device of claim 9, wherein thepreamplifier circuitry is further configured to activate the reader biascurrent after warming up the reader circuitry.
 12. The device of claim9, wherein the write operation is a plurality of alternating writesignal operations.
 13. The device of claim 12, wherein the preamplifiercircuitry is further configured to warm up the reader circuitry duringone of the alternating write signal operations.